diff --git a/README.md b/README.md
index 1e28bbc..562b596 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,21 @@
 # imago
-Image saving & comparing tool for go.
+Image saving & comparing tool for go based on webp.
+
+## Functions
+### func Str2bytes(s string) []byte
+Fast convert
+### func Bytes2str(b []byte) string
+Fast convert
+### func GetDHashStr(img image.Image) (string, error)
+Get image dhash encoded by [go-base16384](https://github.com/fumiama/go-base16384)
+### func HammDistance(img1 string, img2 string) (int, error)
+Get hamming distance between two dhash strings
+### func Scanimgs(imgdir string) error
+Scan all images like 编码后哈希.webp
+### func Pick(exclude []string) string
+Pick a random image
+### func Saveimgbytes(b []byte, imgdir string, uid string, force bool) string
+### func Saveimg(r io.Reader, imgdir string, uid string) string
+Save image into imgdir with name like 编码后哈希.webp
+### func Addimage(name string)
+manually add an image name into map
\ No newline at end of file
diff --git a/data.go b/data.go
new file mode 100644
index 0000000..fc039ee
--- /dev/null
+++ b/data.go
@@ -0,0 +1,34 @@
+package imago
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"unsafe"
+)
+
+// Str2bytes Fast convert
+func Str2bytes(s string) []byte {
+	x := (*[2]uintptr)(unsafe.Pointer(&s))
+	h := [3]uintptr{x[0], x[1], x[1]}
+	return *(*[]byte)(unsafe.Pointer(&h))
+}
+
+// Bytes2str Fast convert
+func Bytes2str(b []byte) string {
+	return *(*string)(unsafe.Pointer(&b))
+}
+
+// bytes82uint64 字节数(大端)组转成int(无符号的)
+func bytes82uint64(b []byte) (uint64, error) {
+	if len(b) == 9 {
+		b = b[:7]
+	}
+	if len(b) == 8 {
+		bytesBuffer := bytes.NewBuffer(b)
+		var tmp uint64
+		err := binary.Read(bytesBuffer, binary.BigEndian, &tmp)
+		return tmp, err
+	}
+	return 0, fmt.Errorf("%s", "bytes lenth is invaild!")
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..d9cfb18
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,9 @@
+module github.com/fumiama/imago
+
+go 1.16
+
+require (
+	github.com/corona10/goimagehash v1.0.3
+	github.com/fumiama/go-base16384 v1.1.0
+	github.com/kolesa-team/go-webp v1.0.0
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..088ec56
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,13 @@
+github.com/corona10/goimagehash v1.0.3 h1:NZM518aKLmoNluluhfHGxT3LGOnrojrxhGn63DR/CZA=
+github.com/corona10/goimagehash v1.0.3/go.mod h1:VkvE0mLn84L4aF8vCb6mafVajEb6QYMHl2ZJLn0mOGI=
+github.com/fumiama/go-base16384 v1.1.0 h1:4npregEpgJ4HtHYNMcw7eabSSO8GIqfG3xGZWtcYcIA=
+github.com/fumiama/go-base16384 v1.1.0/go.mod h1:YCaxEQyBX717X2lMlJvdccNhA83zhKRR/ipPOIIIQj8=
+github.com/kolesa-team/go-webp v1.0.0 h1:HFE7NhW1jkM59HgUwRdcSJ+VVZz7F1RZk6VFY27YZpQ=
+github.com/kolesa-team/go-webp v1.0.0/go.mod h1:P0sDD6OLl4jBVcwCcYRuu1C+kUrR4V19LYWs+yV3UcY=
+github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646 h1:zYyBkD/k9seD2A7fsi6Oo2LfFZAehjjQMERAvZLEDnQ=
+github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646/go.mod h1:jpp1/29i3P1S/RLdc7JQKbRpFeM1dOBd8T9ki5s+AY8=
+golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d h1:RNPAfi2nHY7C2srAV8A49jpsYr0ADedCk1wq6fTMTvs=
+golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d/go.mod h1:023OzeP/+EPmXeapQh35lcL3II3LrY8Ic+EFFKVhULM=
+golang.org/x/text v0.3.6 h1:aRYxNxv6iGQlyVaZmk6ZgYEDa+Jg18DxebPSrd6bg1M=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
diff --git a/imgdiff.go b/imgdiff.go
new file mode 100644
index 0000000..dcc3774
--- /dev/null
+++ b/imgdiff.go
@@ -0,0 +1,48 @@
+// Package imago 图片处理相关
+package imago
+
+import (
+	"encoding/binary"
+	"image"
+
+	"github.com/corona10/goimagehash"
+	base14 "github.com/fumiama/go-base16384"
+)
+
+var lastchar = "㴁"
+
+func decodeDHash(imgname string) *goimagehash.ImageHash {
+	b, err := base14.UTF82utf16be(Str2bytes(imgname + lastchar))
+	if err == nil {
+		dhb := base14.Decode(b)
+		if dhb != nil {
+			dh, err1 := bytes82uint64(dhb)
+			base14.Free(dhb)
+			if err1 == nil {
+				return goimagehash.NewImageHash(dh, goimagehash.DHash)
+			}
+		}
+	}
+	return nil
+}
+
+// HammDistance Get hamming distance between two dhash strings
+func HammDistance(img1 string, img2 string) (int, error) {
+	b1 := decodeDHash(img1)
+	b2 := decodeDHash(img2)
+	return b1.Distance(b2)
+}
+
+// GetDHashStr Get image dhash encoded by go-base16384
+func GetDHashStr(img image.Image) (string, error) {
+	dh, err := goimagehash.DifferenceHash(img)
+	if err == nil {
+		data := make([]byte, 8)
+		binary.BigEndian.PutUint64(data, dh.GetHash())
+		e := base14.Encode(data)
+		b, _ := base14.UTF16be2utf8(e)
+		base14.Free(e)
+		return string(b)[:15], nil
+	}
+	return "", err
+}
diff --git a/storage.go b/storage.go
new file mode 100644
index 0000000..63c0c0a
--- /dev/null
+++ b/storage.go
@@ -0,0 +1,169 @@
+package imago
+
+import (
+	"bytes"
+	"fmt"
+	"image"
+	"io"
+	"math/rand"
+	"net/url"
+	"os"
+	"strings"
+	"sync"
+
+	"github.com/kolesa-team/go-webp/decoder"
+	"github.com/kolesa-team/go-webp/encoder"
+	"github.com/kolesa-team/go-webp/webp"
+)
+
+var (
+	images = make(map[string][]string)
+	mutex  sync.Mutex
+)
+
+func Imgexsits(name string) bool {
+	index := name[:3]
+	tail := name[3:]
+	tails, ok := images[index]
+	if ok {
+		found := false
+		for _, t := range tails {
+			if tail == t {
+				found = true
+				break
+			}
+		}
+		return found
+	}
+	return false
+}
+
+// Addimage manually add an image name into map
+func Addimage(name string) {
+	index := name[:3]
+	tail := name[3:]
+	mutex.Lock()
+	defer mutex.Unlock()
+	if images[index] == nil {
+		images[index] = make([]string, 0)
+		fmt.Println("[addimage] create index", index, ".")
+	}
+	images[index] = append(images[index], tail)
+	fmt.Println("[addimage] index", index, "append file", tail, ".")
+	images["sum"] = append(images["sum"], name)
+}
+
+// Saveimgbytes Save image into imgdir with name like 编码后哈希.webp
+func Saveimgbytes(b []byte, imgdir string, uid string, force bool) string {
+	r := bytes.NewReader(b)
+	img, _, err := image.Decode(r)
+	iswebp := false
+	if err != nil {
+		r.Seek(0, io.SeekStart)
+		img, err = webp.Decode(r, &decoder.Options{})
+		if err == nil {
+			iswebp = true
+		} else {
+			fmt.Printf("[saveimg] decode image error: %v\n", err)
+			return "\"stat\": \"notanimg\""
+		}
+	}
+	dh, err := GetDHashStr(img)
+	if err != nil {
+		return "\"stat\": \"dherr\""
+	}
+	if force && Imgexsits(dh) {
+		return "\"stat\":\"exist\", \"img\": \"" + url.QueryEscape(dh) + "\""
+	} else {
+		for _, name := range images["sum"] {
+			diff, err := HammDistance(dh, name)
+			if err == nil && diff < 10 { // 认为是一张图片
+				fmt.Printf("[saveimg] old %s.\n", name)
+				return "\"stat\":\"exist\", \"img\": \"" + url.QueryEscape(name) + "\""
+			}
+		}
+	}
+	f, err := os.Create(imgdir + dh + ".webp")
+	if err != nil {
+		return "\"stat\": \"ioerr\""
+	}
+	defer f.Close()
+	if !iswebp {
+		options, err := encoder.NewLossyEncoderOptions(encoder.PresetDefault, 75)
+		if err != nil || webp.Encode(f, img, options) != nil {
+			return "\"stat\": \"encerr\""
+		}
+	} else {
+		r.Seek(0, io.SeekStart)
+		c, err := io.Copy(f, r)
+		if err != nil {
+			return "\"stat\": \"ioerr\""
+		}
+		fmt.Printf("[saveimg] save %d bytes.\n", c)
+	}
+	fmt.Printf("[saveimg] new %s.\n", dh)
+	return "\"stat\":\"success\", \"img\": \"" + url.QueryEscape(dh) + "\""
+}
+
+// Saveimg Save image into imgdir with name like 编码后哈希.webp
+func Saveimg(r io.Reader, imgdir string, uid string) string {
+	imgbuff := make([]byte, 1024*1024) // 1m
+	r.Read(imgbuff)
+	return Saveimgbytes(imgbuff, imgdir, uid, false)
+}
+
+// Scanimgs Scan all images like 编码后哈希.webp
+func Scanimgs(imgdir string) error {
+	entry, err := os.ReadDir(imgdir)
+	if err != nil {
+		return err
+	}
+	for _, i := range entry {
+		if !i.IsDir() {
+			name := i.Name()
+			if strings.HasSuffix(name, ".webp") {
+				name = name[:len(name)-5]
+				if len([]rune(name)) == 5 {
+					Addimage(name)
+				}
+			}
+		}
+	}
+	return nil
+}
+
+func namein(name string, list []string) bool {
+	in := false
+	for _, item := range list {
+		if name == item {
+			in = true
+			break
+		}
+	}
+	return in
+}
+
+// Pick Pick a random image
+func Pick(exclude []string) string {
+	sum := images["sum"]
+	le := len(exclude)
+	ls := len(sum)
+	if le >= ls {
+		return ""
+	} else if le == 0 {
+		return sum[rand.Intn(len(sum))]
+	} else if ls/le > 10 {
+		name := sum[rand.Intn(len(sum))]
+		for namein(name, exclude) {
+			name = sum[rand.Intn(len(sum))]
+		}
+		return name
+	} else {
+		for _, n := range sum {
+			if !namein(n, exclude) {
+				return n
+			}
+		}
+		return ""
+	}
+}